Carburetor choke control mechanism



July 19, 1938. M. BROWN ,5

CARBURETOR CHOKE CONTROL MECHANISM Filed June 29, 1957 I INVENTOR. M02241 6. EEO/40v ATTORNEY.

gases from the stove to the housing.

Patented July 19, 193$ PATENT OFFICE CARBURETOR CHOKE CONTROL MECHAN! Morris Brown, Detroit, Mich. Application June 29, 1937, Serial No. 150,956

10 Claims.

This invention relates to carburetors for internal combustion engines and consists particularly in novel means for controlling thermostatic choke operating mechanism.

An automatic choke carburetor of the usual type for automobile engines is provided with a thermostat for influencing the choke valve and some means for heating the thermostat in cor respondence to the temperature of the engine manifolds and firing chambers. Frequently this is accomplished by means of a stove orheating chamber secured to the exhaust manifold or other convenient part and connected to the thermostat housing by tubing for conducting heated Exposing the thermostat housing and stove to suction in the'intake manifold has also been suggested in order to, insure an adequate flow of heated gases past the thermostat. In such case, air adjacent the engine, which may contain oil or dust particles or other impurities, is drawn into the housing and engine firing chamber and may foul the thermostatic mechanism and suction connections.

Moreover, where a separate stove is provided this must be connected with the thermostat housing by a substantial length of tubing which complicates assembly of the automatic choke mechanism and results in loss of heat.

.An object of the present invention is to provide means for supplying relatively clean, heated air to the thermostat housing.

Another object is to provide a carburetor and manifold construction which includes the thermostat heating means as a unitary part thereof, thus eliminating the separate stove heretofore used.

These objects and other more detailed objects hereafter appearing are attained by the structure illustrated inwhich.

The figure is a sectional view of a carburetor Showing portions of the automatic choke mecha-, nism and engine manifolds.

The carburetor shown is, in general,' of well known form having a downdraft mixture conduit including an air inlet horn l, venturis 2, and

outlet portion 3 flanged as at 4 for attachmentbymeans of bolts 5 to the riser or hot spot" portion 6 of the manifold construction. A butterfiy choke valve 1 is mounted in the air horn on shaft 8 and a throttle valve 9 is pivoted adjacent the outlet portion of the carburetor. An air cleaner 9 of any suitable construction is secured 'to the air inlet horn.

Adjacent the mixture conduit is a bowl having the usual float operated mechanism (not shown) for maintaining fuel therein at a substantially constant level. Fuel from bowl I is supplied to the mixture conduit through main nozzle l I and idling passage l2 discharging adjacent the throttle valve. Y

Choke valve I is controlled, for cold starting and warm up purposes, by mechanism including a housing 13 enclosing a spiral, bi-metal thermostat I 4 and the small cylinder l slidably receiving piston l6. Coil I4 is secured at its inner end to a pintle l'l projecting from the housing wall and at its outer end has a hook l8 receiving a lateral finger IS on a crank pivotally carried by the housing and rigid with an arm 2| between the housing and mixture conduit. Arm 2| is connected to choke lever 22 by a rod 23.

Cylinder I5 communicates with the interior of the mixture conduit posterior to throttle 9 by means of ,a suction connection 24. Longitudinal grooves 25 in the wall of cylinder l5 provide for transmission of a portion of the suction to the interior of housing l3. The described choke control mechanism corresponds substantially with that more fully described and claimed in Coffey Patent No. 2,085,351 except that in the present instance the thermostat housing is mounted adjacent the outlet portion of the carburetor instead of on the air horn. For the purposes of the present invention, the thermostatic housing I may be located in any convenient position.

The intake manifold 26 is shown formed integrally with the exhaust manifold 21, a portion of the latter extending around the riser portion 28 of the intake manifold, as at 29, to form the usual hot spot. construction. Also formed integrally with the hot spot construction isa chamber 30 which is sealed from the interiors of both the intake and exhaust manifolds. A longitudinal orifice 3|, formed in the wall of the carburetor mixture conduit, communicates at its upper end with the air inlet portion of the conduit and, at its lower end, connects with chamber 30 through passage 3la in the riser portion. A portion of chamber '30 spaced from passage 3| has a connection 32, 320. with the interior of thermostat housing l3. Thus suction applied to the interior of housing l3 draws heated gases from the carburetor air horn through heating chamber or stove 30 into the housing. All such heated gases are first strained through the air cleaner for removing impurities.

By means of the illustrated construction, the

' entire carburetor including the automatic choke control mechanism is formed as a compact unit and also the heater and manifolds are formed duit, and control mechanism for said valve inv together. These structures may be assembled by mrely bolting the carburetor flange to the manifold riser, passage 3|, 3m and 32 and 3Za being disposed to register properly. Air strained through the air cleaner'is drawn into the thermostat housing, which prevents the thermostat mechanism and choke connections from being fouled by impurities. This is an important feature in automobiles where the air under the hood is frequently contaminated with grit, oil, or dust.

In the present instance, the connection between the stove or heater chamber and the carburetor inlet is formed as a longitudinal orifice integral with the wall of the carburetor mixture conduit and .the other heater and suction connections with the thermostatic housing are relatively short. Where the thermostat is mounted adjacent the ainhom, these connections will necessarily be varied to correspond, it being contemplated that wherever practical the passages will be formed in the carburetor walls. It maybe desirable to construct one or more of the heat and suction connections as separate tubing.

The exclusive use of allgsuch modifications as come within the scope of the appended claims is contemplated.

Iclaim: I

1. In combination; a carburetor including a mixture conduit and a choke valve in said concluding a thermostat housing and means for supplying heated gases to said housing including a stove having an inlet connection into the interior of said conduit, and suction connections between said housing and said stove and between said housing and a portion of said conduit normally at lower-operating pressure than said inlet -connection.

2. Structure as specified in claim 1 further including an air cleaner through which all air to mostat therein, a stove arranged to supply heated gases to said housing, and a connection between said stove and said air inlet whereby a portion of the air entering said inlet is heated in said stove.

5. Structure as specified in claim a in which all the gases supplied to said stove are drawn from said carburetor inlet.

6. In an internal combustion engine, an intake passage, an exhaust passage including a portion adjacent said intake passage for heating the same, means forming a chamber in a wall of said exhaust passage, and carburetor choke control mechanism including a thermostat housing. and a connection between said chamber and said housing-for supplying heated gases to said housing. v

'7. In an internal combustion engine, intake and exhaust manifolds, said intake and exhaust manifolds having portions separated by a common wall forming a hot spot constructionfor applying heat to the engine intake passage, a chamber in a wall of said, hot spot construction, and carburetor choke control mechanism including a thermostat housing and a connection between said chamber and said housing for supplying heated gases to said chamber.

8. In an internal combustion engine, an intake passage including a carburetor mixture conduit,

a choke valve in said conduit, an exhaust passage including a part contacting said intake passage for heating the same, a stove associated with said part, and choke control mechanism including a thermostat housing and connections for drawing gases from the inlet portion of said mixture conduit through said stove and said housing and back into said intake passage, at least one of said connections being formed as alongitudinal orifice in the wall of said conduit.

9. Structure as specified in claim 8 in which said thermostat housing is located adjacent the outlet portion of said mixture conduit, the connection between said stove and the inlet portion of said conduit extending along and-being formed integrally with the wall of said conduit. 10. In an internal combustion engine, intake and exhaust manifolds including hot spot construction, a portion of said construction compris- 

